Senior Software Engineer, Inference

AssemblyAI, Inc.; Greater London; On-site; GBP 120,000 - 145,000; Full time

Job summary

AssemblyAI is hiring a Software Engineer to transform cutting-edge AI research into production-ready APIs used by customers daily. You’ll bridge the research org and Applied teams, taking new model capabilities from proof of concept to scalable, well-documented APIs that handle production traffic at scale.

You will design customer-facing APIs, scale inference infrastructure for millions of users, and collaborate with researchers to turn notebooks into reliable, latency-conscious products.

Qualifications

• Strong backend engineering experience in production environments.
• Experience with ML infrastructure and APIs serving models at scale.
• Ability to design robust, customer-facing APIs and maintain them over time.

Responsibilities

• Design and ship customer-facing APIs that expose new model capabilities, owning them from prototype through launch and ongoing iteration.
• Scale inference infrastructure to support 1M+ API users.
• Collaborate with researchers to productionize new techniques and turn ideas into reliable systems.
• Understand how customers build with our products and feed insights back into product and research directions.
• Contribute across the stack including backend services, inference infra, SDKs, and internal tooling.

Skills

Backend engineering

ML infra

Production APIs

Collaboration

Job description

AssemblyAI builds the best-in-class Voice AI models powering the next generation of voice applications. We have a lab, and we also power our own models in our own proprietary inference environment. Our models serve 500M+ inference calls monthly, and process nearly 2 million hours of audio daily. The Voice AI space is at an inflection point; we’re looking for the best talent we can find to join a rapidly scaling team that's defining the future of the industry.

We are one of the most capital-efficient AI companies on the planet - and are rapidly approaching $1M ARR per employee. We sit among the top 5 most revenue-dense teams within the fastest-growing AI companies today. We have thousands of customers building with us including the top startups and world-renowned enterprises, and are serving at tremendous scale: we process nearly 2 million hours of audio daily and handle more than 15 million API calls every day. This is a rare growth-stage opportunity where the business is proven, the revenue is durable, and the growth trajectory is steep and getting steeper. We have a super flat culture and expect our employees to be deeply intimate with the details at all levels.

If you've ever felt buried under layers of bureaucracy, starved of real ownership, or frustrated watching your work disappear into a slow-moving org, AssemblyAI is built differently. The company operates as a true meritocracy, with no heavy planning or approval processes and no gatekeeping on the tools or information you need. For anyone who genuinely cares about voice AI, not as a trend to chase, but as a technology to build, this is the place where the most interesting problems at the most interesting scale are being solved by a team small enough that you'll actually know everyone's name.

Why AssemblyAI

AssemblyAI builds the best-in-class Voice AI models powering the next generation of voice applications. We have a lab, and we also power our own models in our own proprietary inference environment. Our models serve 500M+ inference calls monthly, and process nearly 2 million hours of audio daily. The Voice AI space is at an inflection point; we’re looking for the best talent we can find to join a rapidly scaling team that’s defining the future of the industry.

We are one of the most capital-efficient AI companies on the planet - and are rapidly approaching $1M ARR per employee. We sit among the top 5 most revenue-dense teams within the fastest-growing AI companies today. We have thousands of customers building with us including the top startups and world-renowned enterprises, and are serving at tremendous scale: we process nearly 2 million hours of audio daily and handle more than 15 million API calls every day. This is a rare growth-stage opportunity where the business is proven, the revenue is durable, and the growth trajectory is steep and getting steeper. We have a super flat culture and expect our employees to be deeply intimate with the details at all levels.

If you've ever felt buried under layers of bureaucracy, starved of real ownership, or frustrated watching your work disappear into a slow-moving org, AssemblyAI is built differently. The company operates as a true meritocracy, with no heavy planning or approval processes and no gatekeeping on the tools or information you need. For anyone who genuinely cares about voice AI, not as a trend to chase, but as a technology to build, this is the place where the most interesting problems at the most interesting scale are being solved by a team small enough that you'll actually know everyone's name.

About the role:

We're hiring a Software Engineer to help turn cutting-edge AI research into products our customers rely on every day. You'll sit on a fast-paced engineering team between our research org and our Applied teams, taking new model capabilities from proof of concept to robust, well-documented APIs serving production traffic at scale.

What You’ll Do:

• Design and ship customer-facing APIs that expose new model capabilities, owning them from prototype through launch and ongoing iteration.
• Scale inference infrastructure to support our 1M+ api users
• Partner with researchers to productionize new techniques. For example, turning a notebook or POC into something with the latency, reliability, and ergonomics customers expect.
• Work with our customers and Applied teams to understand how users are building with our products, and feed that back into product design and research direction.
• Contribute across the stack as needed: backend services, inference infrastructure, SDKs, internal tooling.

What You’ll Need:

• Strong backend engineering experience, including building and supporting machine learning infrastructure and/or customer-facing APIs in production.
• Comfort operating with ambiguity. Research timelines and product timelines don't always line up, and you're energized rather than frustrated by that.
• Genuine curiosity about AI/ML. You don't need to be a researcher, but you should want to understand what the models are doing well enough to make good engineering decisions around them.
• Strong collaboration skills. You'll be working daily with researchers, applied engineers, and sometimes customers, people with very different contexts and priorities, and the role only works if you enjoy that.

Pay Transparency:

AssemblyAI strives to recruit and retain exceptional talent from diverse backgrounds while ensuring pay equity for our team. Our salary ranges are based on paying competitively for our size, stage, and industry, and are one part of many compensation, benefit, and other reward opportunities we provide.

There are many factors that go into salary determinations, including relevant experience, skill level, qualifications assessed during the interview process, and maintaining internal equity with peers on the team. The range shared below is a general expectation for the function as posted, but we are also open to considering candidates who may be more or less experienced than outlined in the job description. In this case, we will communicate any updates in the expected salary range.

The provided range is the expected salary for candidates in the United Kingdom. Outside of those regions, there may be a change in the range which will be communicated to candidates throughout the interview process.

Salary range: £ 120,000 - £ 145,000

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Keep exploring AssemblyAI

Transcribe:

Speech-to-Text | Streaming Speech-to-Text

Understand:

Speech Understanding | LLM Gateway

Interact:

Voice Agent API | Dictation API

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